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Type of test data needed for hyperelastic bubble expansion

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Posts: 8
Topic starter
(@Martin_Polytechnique)
Active Member
Joined: 15 years ago

I am expanding a latex tube (capped off at one end) by filling it with water driven by a specific pressure. I have the following questions about modeling the tubes behavior using Abaqus:

1. The only test I could perform on the constituent material is uniaxial tension. However, I get 2 different stress/strain curves for material pieces cut longitudinally from the tube and those cut laterally (as in a material strip that runs along the tube and a ring cut out from the tube and cut to make a strip). Which stress/strain curve should I use?

2. No matter which stress/strain curve I use, I get expansion results that are an order of magnitude (or even more) smaller than what I see from empirical testing. I tried scaling the stress/strain curve until I see the same value for expansion I see experimentally, is this a reasonable method of approach?

3. In order to get reliable results for hyperelastic balloon expansion, is uniaxial data enough? If not, what others tests are required (biaxial, volumetric, etc.,)?

4. Last, but not least, since the balloon fills up rather quickly, is there a way to model the expansion dynamically? I saw a dynamic loading example in the abaqus manual (the dynamically loaded cargo crane), but the trusses it uses are not made from a hyperelastic material. So, to restate, can Abaqus handle dynamic hyperelastic modeling?

If you could provide assistance on any of these questions (or feel free to help with all of them :grin:), I would greatly appreciate it.

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Posts: 3998
(@jorgen)
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Joined: 5 years ago

I have done quite similar analyses and have good experience analyzing latex material. Here are a few comments:

1) If you get two difference responses in the two directions then you should probably use an anisotropic hyperelastic or anisotropic viscoleastic material model. You cannot really pretend that the material is the same in all directions if it is not.

2) That is quite strange. Is your experimental uniaxial data obtained at a similar strain rate as your empirical testing? Are you sure you are using an appropriate material model? You should be able to get a much more accurate result.

3) Uniaxial data in two directions should give you relatively accurate predictions. If you can perform biaxial tension that would be a useful addition.

4) Yes, you can use Abaqus/Explicit if you want to include dynamic (inertial) effects.

-Jorgen

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Posts: 8
Topic starter
(@Martin_Polytechnique)
Active Member
Joined: 15 years ago

Thanks,

As always, your feedback is very helpful. I did figure out that I wasnt taking dynamic effects into account (different strain rate for the balloon inflation).

I greatly appreciate your help.

Best,

-P

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Posts: 8
Topic starter
(@Martin_Polytechnique)
Active Member
Joined: 15 years ago

Jorgen,

You mentioned that you conducted testing similar to balloon inflation. Did you run your model as a dynamic one? If it is not proprietary, do you mind sharing your model set up? Im currently trying to model inertial effects using MATLAB and a look up table which has different volume-pressure data for my balloon which was obtained quasi-statically (very slow inflation) and would really like to have something in Abaqus to compare my results to.

If you cant share your model, do you mind pointing out some key aspects of creating a dynamic inflation model?

Thanks again for all your help.

-P

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Posts: 3998
(@jorgen)
Member
Joined: 5 years ago

I used both static and dynamic approaches, but unfortunately I cannot share the files.

I did not use any particular trick. I based my analysis of simple examples and the text from the Abaqus manuals.

Do you have any specific questions?

-Jorgen

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Posts: 3
(@tliu892)
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Joined: 9 years ago

Hyperelstic and viscoelastic model

Hello everybody

I have a question please. Well i would like to model an elastomeric ring that is supposed to used as an elstomeric ligature in orthodontic field. I Hvae not any idea about the constitutive model to choose to model my ring. It deforms greatly so that i think about using hyperelastic material. Also ther is relaxation through time. I think also about viscoelastic. Would you help me please how to medl this in abaqus.

THansk a lot

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